Study On Preparation And Reaction Kinetics Of Sucralose By Deacetylation Of Sucralose-6-acetate

Sucralose(TGS)is a new type of high-intensity sweetener,and it is the most perfect synthetic high-intensity sweetener so far.The sweet taste is very close to the natural sucrose,and its chemical properties are very stable,which isn't sensitive to the light,heat and pH.Moreover,it is low calorie and high safety performance.These advantages of sucralose are very consistent with the healthy diet requirement of modern society,so the demand of sucralose will get larger and larger,on a global scale.The main topic of this study is for the last step of the mono-group protection in the production of sucralose,namely the deacetylation of sucralose-6-acetate reaction.Firstly,the main reactants and products were analyzed qualitatively,and the reaction mechanism of the side reaction was speculated.Secondly,sodium methoxide/methanol was used as catalyst,and the batch stirred tank was used as reactor.In the homogeneous system,the deacetylation of sucralose-6-acetate reaction kinetics was studied,and the kinetics model was established.Lastly,the continuous process conditions for sucralose were explored in the smooth periodic contraction oscillatory flow reactor.This thesis reaches some conclusions as following:(1)Liquid chromatography,mass spectrometry and nuclear magnetic resonance spectrometer analysis instrument were used to analysis sucralose,sucralose-6-acetate,and by-products in the process of deacetylation.The unknown by-product,which has a bad taste for the sucralose,is mono-chloro-galacto-sucrose(MGS),and its formula is C12H21O10Cl1.The other by-product is tetra-chloro-galacto-sucrose,and its formula is C12H18O7Cl4.What is more,the reaction mechanism of the side reaction was speculated,which put forward the direction for the further research.(2)In the batch stirred tank,our experiment examined the influences of the dosage of catalyst,the reaction temperature and the ratio of raw materials on the reaction rate of sucralose-6-acetate.Experimental results show that,the higher the reaction temperature,the faster the reaction rate,but the energy will be increased if temperatures get too high.The higher the dosage of catalyst,the faster the reaction rate,but the side reaction will be caused if the dosage gets too much.The lower the raw material concentration,the faster the reaction rate,the shorter the reaction time,and the lower yield of the sucralose.According to the determination of the reaction kinetics data,the reaction kinetics model was established.The reaction kinetics model is:r =kCA1.5,where k = 2.5032 ×1011 exp(-60401.2/RT)?(3)In the smooth periodic contraction oscillatory flow reactor,we examined the influences of oscillation frequency,oscillation amplitude,reaction temperature,catalyst dosage,reaction time and the way of catalyst feeding on the reaction rate of sucralose-6-acetate.The optimal technological conditions are as follows:oscillation frequency is 1 Hz,amplitude is 1.904 cm,reaction temperature is 30 ?,dosage of catalyst is 0.90%(W%),the reaction time is 17.5 min,the way of catalyst feeding is three stocks.In the technological conditions,the mass fraction of sucralose is more than 97%,and the mass fraction of sucralose-6-acetate is lower than 0.3%.